Heretofore, a solid preparation printing apparatus (tablet printing apparatus) described in Patent Literature 1 has been known. In the solid preparation printing apparatus, a printing mechanism that performs printing (transfer) by a transfer roller prints characters, marks and the like on surfaces of solid preparations (tablets) sequentially conveyed by a conveyor (conveyor belt). In the conveyor, pockets having a minute hole are arranged in the conveying direction thereof, and the solid preparations are sequentially conveyed by the conveyor moved with the solid preparations accommodated in the pockets. Then, an air suction part that sucks in air through the minute hole of each pocket is provided on the rear side of a part of the conveyor opposite to the transfer roller. The solid preparation, which is taken in each of the part opposite to the transfer roller of the conveyer, is certainly held in the pocket by air suctioning action of the air suction part. This enables the transfer roller to accurately transfer (print) characters, marks and the like without a printing misalignment on the solid preparation held in each pocket. In such a solid preparation printing apparatus, the characters, marks and the like to be printed are changed by replacing the transfer roller with a desired transfer roller to print.